A Role for Inorganic Ions in the Maintenance of Intracellular Solute Concentrations in a Marine Pseudomonad

Abstract

ONE of the earliest observations of a physiological nature made by marine microbiologists was that marine bacteria prefer sea water or a solution of sodium chloride to fresh water in the medium for growth¹. Recent studies have shown that the need of marine bacteria for sea water in chemically denned media represents a requirement for inorganic ions² and that inorganic ions play at least two essential parts in the growth and survival of the cells. First, inorganic ions are required for the nutrition and metabolism of marine bacterial cells. Specific requirements for a number of the ions of sea water for growth^3,4, oxidative metabolism⁵ and active transport⁶ have been demonstrated. Secondly, inorganic ions are required to prevent lysis of marine bacterial cells. Studies with a marine pseudomonad have shown that the requirement for inorganic salts to maintain the integrity of the cells in a suspending medium is not due to the osmotic activity of the salts in solution but to the fact that inorganic ions are intimately involved in maintaining the mucopeptide layer of the cell wall intact⁷.